Do they look like huge carpenter bees?

If so, they are Giant Resin Bees.

These are massive bees, their wings are so large they remind me of a small dragonfly!

The are originally from Asia, and appeared in the Carolinas a few years ago. No one knows how they got here.

They may look threatening, but they are totally harmless. Well, the females can sting, but won't unless you step on them.

A fun bee to watch... mine seem to prefer Agastache (Hummingbird Mint) & Nepeta (Cat Mint).

The link below is not actually a bee, but a type of wasp. It is large, has yellow and black backside, brownish-orange wings. It stings a cicada and buries it in the ground, paralized but alive and plants its eggs with it, where they hatch and have something to eat. Yuck. I think that the females can sting but usually use their "stinger" for ova-positioning. Males just buzz you to defend the territory. Thought this might be what you have seen.
hortster

Here is a link that might be useful: {{gwi:432622}}